Measurement of Coagulation Process of Soymilk by a Rotational Viscosimeter (Viscograph)

Studies on Cogulation Process of Soymilk in Tofu and Kori-tofu Manufacture. Part III

Abstract

For measuring and controlling of coagulation process of soymilk, a new computerized measurement of rotational viscosity change of soymilk was investigated by use of the reformed Blabender Viscograph. The coagulant, 1M calcium chloride solution, was continuously added into soy milk which was contained in the rotating vessel of Viscograph. The three parameters, MV (maximum viscosity), FV (flat viscosity) and MVT (time For MV) were adopted to evaluate coagulation process of soy milk. The increased coagulation temperaure lowered both MV and MVT, but increased FV. A rotation speed of the reaction vessel much affected MVT, though MV was kept almost constant. Neither pottasium chloride nor sucrose which were previously added to soy milk affected MVT, comparable to their effects on Xml, "point of critical concentration of coagulant", in the electrochemical experiments reported previously. The concentration of soymilk was also found to be an important factor affecting these parameters. Further, a relationship between the viscographic parameters and Xml was investigated for a series of soymilks prepared from 19 varieties of soybeans, demonstrating that MVT correlated with Xml (r=0.862, p<0.01). The significance of MV as well as FV with respect to hardness of tofu was also discussed.